Surface Tunneling Currents in Reverse Biased Narrow Bandgap P-N Junction

The importance and dominance of surface related effects on the reverse current characteristics of narrow bandgap p-n junctions is demonstrated and studied by measuring InSb gate-controlled diodes characteristics. The geometrical location where reverse surface breakdown currents are developed is the high field region near the intersection of the metallurgical junction with the semiconductor - insulator interface. Direct band- to-band tunneling mechanism is proposed as the physical source of these breakdown currents and a novel 2-D theoretical model is developed for their integration. This model is based on a detailed solution of Poisson equation at each gate-controlled diode operating point, i.e. at each diode and gate voltages. The model predictions are corroborated by comparison to the experimental current measurements. The proposed model strengthen our understanding of breakdown currents origin in narrow bangap p-n junctions, and enables quantitative estimations of direct hand-to-hand tunneling currents in 2-D surface regions.